Drying ei ement,chemical composition and process

ABSTRACT

A LIQUID PERMEABLE, DRYING ELEMENT, SUCH AS A THIN COATING, CONTAINING AN ORGANIC POLYMERIC DESICCANT CROSSLINKED TO A POLYMER, FOR EXAMPLE CROSS-LINKED TO A SUPPORT COMPRISING A POLYMER, WHICH CAN BE THE SAME AS THE ORGANIC DESICCANT OR DIFFERENT FROM THE ORGANIC, POLYMERIC DESICCANT, RAPIDLY REMOVES DIFFUSIBLE LIQUID, ESPECIALLY WATER, FROM A PERMEABLE SOLID. A DRYING ELEMENT, AS DESCRIBED, CAN BE USEFUL FOR REMOVING DIFFUSIBLE LIQUID FROM LAYERS OF A PHOTOGRAPHIC ELEMENT SUCH AS PHOTOGRAPHIC FILM.

United States Patent ABSTRACT OF THE DISCLOSURE A liquid permeable, drying element, such as a thin coating, containing an organic, polymeric desiccant crosslinked to a polymer, for example cross-linked to a support comprising a polymer, which can be the same as the organic desiccant or different from the organic, polymeric desiccant, rapidly removes diffusible liquid, especially water, from a permeable solid. A drying element, as described, can be used for removing diifusible liquid from layers of a photographic element, such as photographic film.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to removing diffusible liquids from liquid permeable solid materials containing such liquids. In one of its aspects, it relates to removing diffusible liquid such as water, from a liquid permeable solid material, such as a moist layer of a photographic element. In another of its aspects, it relates to drying a moist colloid coating by intimately contacting the moist coating with a coating containing an organic, polymeric desiccant cross-linked to a polymer, especially a support comprising the polymer. In a further aspect of the invention, it relates to cross-linking an organic, polymeric desiccant with an aldehyde, such as formaldehyde, to a polymer which may be the organic, polymeric desiccant or a polymer different from said organic desiccant, during coating.

Description of the prior art Two methods have generally been used heretofore for removing liquids from permeable solids containing such liquids. In one method, liquid is removed by evaporation, for example, by a combination of heating and/or reducing pressure around the solid material. In the second method, the solid material is immersed in an extractant, such as removing moisture from a moist photographic element by immersing the moist element in an extractant as set out in US. Pat. 2,150,757 of Bodine, issued Mar. 14, 1939.

These methods have not been satisfactory in many cases, especially for removing moisture from photographic elements, since they require costly equipment, such as apparatus for forcing heated air over the solid material, require excessive time, and/or cause undesirable changes in the materials dried.

In the case of photographic elements, it has been usual practice to process such elements after exposure in solutions or processing baths which produce a wet or moist product. It has been necessary in such cases to wait, often for many minutes, for the film, paper, or the like, to dry before further processing or handling, such as contact printing, can be carried out. This time can be reduced by forced air drying at elevated temperatures, but this method has not been entirely satisfactory for removing diffusible liquid from a photographic element in a matter of seconds without undesired effects to the element.

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Drying of photographic elements processed without use of conventional processing baths and where inspection of the processed element as soon as possible is desirable has been especially important. For exampl in aerial reconnaissance, in radiology, and the like, it is necessary to have the processed photographic element in dry condition quickly to determine results, to determine whether another exposure should be made, and/or for other purposes. One method which has been advantageous in decreasing the time from exposure to finished product, without the use of conventional processing baths, employs a wet or moist, absorbent web containing processing agents, typically a monobath, which is contacted \m'th the exposed element for a desired length of time. This method and means for carrying out the method are set out, for example, in US. Pat. 3,179,517 of Tregillus et al., issued Apr. 20, 196 5. One disadvantage of this method, however, is that the resulting processed photographic element is moist, as in other processes, after the film and web are separated and usually must be dried in some manner. Efforts to dry such a photographic element have included application of a powdered inorganic drying agent, such as barium oxide, calcium chloride, activated alumina, and the like, dusted over the surface of the moist element or located on the surface opposite the film of a protective porous web which is contacted with the moist film. This is disclosed in British Pat. 1,012,391 issued Dec. 8, 1965. In the case where the inorganic drying agent is dusted over the surface of the moist photographic element, undesired adherence of the inorganic drying agent to the surface of the element can occur. On the other hand, when the moist photographic element is contacted with a semi-permeable membrane which in turn is contacted with an inorganic drying agent, additional means can be required for contacting the semipermeable membrane with the inorganic drying agent and removal of moisture can be less eflicient than in the case of direct contact of the inorganic drying agent with the moist element.

Other attempts to dry a wet or moist photographic element are disclosed in US. patent application Ser. No. 693,139 of Paul W. Faulhaber, filed Dec. 26, 1967, and US. patent application Ser. No. 693,542 of Frank W. Jackson and Bernard R. Rumbutis filed Dec. 26, 1967, now US. Pat. No. 3,448,528. The inventions disclosed in these applications involve a flexible, liquid permeable, drying elements. A typical drying element described in these applications comprises about 10%, by weight, poly- (ethylene oxide) having an average molecular weight of about 6,000 to about 7,500 with about by weight, of high molecular poly(ethylene oxide) e.g., having an average molecular weight of from about 100,000 to about 5,000,000 or more, on a support. The high molecular weight binder in such a drying element, e.g., poly(ethylene oxide) having an average molecular weight of about 100,- 000 to about 5,000,000, is useful in order to prevent contamination of the photographic element being dried by transfer of the lower molecular weight poly(ethylene oxide) to the photographic element.

The coating composition employed in preparing such drying elements is high in viscosity, mainly due to the high molecular weights of the components of the compositions. This has caused difiiculty in preparing such coatings.

There has accordingly been a need for the polymeric, organic desiccant that can be coated from compositions which have suitable coating viscosity in addition to having desired drying characteristics. The drying element needed was one which (a) provided means to remove diffusible liquids, such as water, from liquid permeable solid materials, such as moist or Wet photographic elements, in a 3 matter of seconds, (b) could be prepared from coating compositions'of'suitable coating viscosities, (c) could be coated quickly and contain a high percent of solids when coated, and (d) did not provide undesired effects on a photographic element.

SUMMARY OF THE INVENTION According to the invention a ditfusible liquid, such as water, is removed from a liquid permeable solid, such as a layer of a photographic element, by directly contacting the solid with a solid, liquid permeable, drying element comprising (a) an organic, polymeric desiccant cross-linked ;with (b) a cross-linking agent, such as an aldehyde, to (c) an organic polymer which can be the same or different from the described polymeric desiccant. This invention provides processes, means and compositions whereby the diffusible liquid can be removed from the permeable solid, such as a photographic element, in a matter of seconds, leaving a photographic element which can be immediately used in further steps, such as in contact printing.

Also, according to the invention, the viscosity of a coating composition from which the described drying element can be prepared is such that greater speed can be used during the coating operation and a higher percentage of solids can be present in the coating composition. The cross-linking reaction of the polymeric desiccant with the cross-linking agent, e.g., formaldehyde, allows low viscosity coating compositions, for the preparation of the drying element, of such characteristics that the composition can set or solidify quickly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of this invention is a liquid permeable, drying element comprising an organic, polymeric desiccant cross-linked with an aldehyde to an organic polymer, which can be the same as the described desiccant and/or an organic polymer diiferent from the described desiccant.

A range of organic, polymeric desiccants can be employed according to the invention. These include any which contain a group which can be cross-linked with a cross-linking agent, such as formaldehyde. These include, for example,

(a) Poly(ethylene oxide) containing acetoacetate end groups, having an average molecular weight of about 200 to about 20,000. The poly(ethylene oxide) is available under the trade name Carbowax, from Union Carbide Corporation, New York, N.Y. This polymer containing acetoacetate end groups can be prepared as described herein,

(b) Poly(acrylamide) and related polyamides,

(c) Polyvinylpyrrolidone,

(d) Alkylene oxide-silicone Copolymers. Compounds of this type are available from Union Carbide Corporation, New York, NY.

(e) Ethylene oxide-propylene oxide copolymers in which the ethylene oxide is at least about 40%, by weight, of the copolymer. Compounds of this type are available under the trade name Pluronic from Wyandotte Chemical Co., Wyandotte, Mich.,

(f) Polyvinyl glycols,

(.g) Urethane resins. Compounds of this type are available, for example, from the Dow Chemical Company, Midland, Mich, under the trade name Voranol.

(h) Polyacryloxy sulfonic acids,

(i) Vinyl ether-maleic anhydride copolymers,

(j) Copolymers of acrylamide with Z-acetoacetoxyethyl methacrylate, e.g., those containing 90% by weight,

acrylamide.

A preferred organic, polymeric desiccant of this invention is a so-called modified poly(ethylene oxide) containing acetoacetate end groups. Typically, the average molecular weight range of such a polymer is about 900 to about 20,000. The described modified poly(ethylene oxide) can be represented by the formula:

oonicni cuicrno cuicnio L J l R p-cngocni In preparing the described polymer (I) containing acetoacetate end groups, polyethylene glycol, having an average molecular weight of about 200 to about 20,000, is mixed in about stoichiometric concentrations with diketene under ambient conditions. The alkylene oxide polymer can be reacted with diketene either in an organic solvent such as methanol or ethanol, in an aqueous solvent, such as water, or a mixture of water with ethylene glycol or, preferably, by melting the polyethylene glycol and reacting it with diketene directly in the absence of any solvent. The reaction proceeds spontaneously at about room temperature and pressure. The reaction produces a modified poly(ethylene oxide) some of whose hydroxyl groups have been converted to acetoacetate groups. The reaction can be carried out in the presence of a catalyst, such as an amine, e.g., triethyl amine or diet-hyl amine, or inorganic alkali, e.g., sodium hydroxide.

The so-called modified poly(ethylene oxide) produced by the reaction with diketene has acetoacetate end groups, which are believed to allow cross-linking in the presence of crosslinking agents.

The modified poly(ethylene oxide) can cross-link with gelatin, such as gelatin on a gelatin coated support and/ or with the same modified poly(ethylene oxide), and/or with a polymer different from the modified poly(ethyleue oxide) which also has acetoacetate end groups and/ or other groups which can crosslink with the described polymers.

Various cross-linking agents can be employed in the practice of the invention. Especially useful cross-linking agents are aldehydes, e.g., those employed in the photographic art as hardening agents, such as formaldehyde,

succinaldehyde and gluteraldehyde. A range of concentration of cross-linking agent can be employed in the coating compositions from which the described drying element is prepared and/ or in the resulting coating. A suitable concentration will depend on several factors, such as the particular polymers employed, the conditions employed for coating, the support, if any, and the like. Usually the concentration is in excess of a stoichiometric concentration.

The polymer to which the described organic, polymeric desiccant is cross-linked can be the same as the organic, polymeric desiccant or different from it, e.g., have a different molecular weight and/or have a different composition. Suitable polymers to which the described organic, polymeric desiccant can be cross-linked include, for example:

(a) Gelatino polymers, such as a gelatin subbing layer commonly employed on supports in the photographic art,

(b) The acetal of disodium 2,4-disulfobenzaldehyde and copoly(vinyl alcohol-vinyl acetoacetate) which is believed to have repeating units of the formula:

(c) Acetoacetylated hydroxy ethyl cellulose which is believed to have repeating units of the formula:

(d) Polyvinyl alcohol containing acetoacetate groups having repeating units of the formula:

wherein the mole ratio of x to y is about 129 to 1.

The organic polymer II as described, can be prepared by dissolving the starting polymer, i.e., poly (vinyl acetal) of 2,4-disulfobenzaldehyde, in an inert solvent, such as dimethyl formamide or dimethyl sulfoxide. A solution of diketene in an inert solvent, such as dimethyl formamide or dimethyl sulfoxide, is added to the resulting composition at elevated temperature, e.g., about 140 C. The desired polymer containing acetoacetate end groups can be precipitated from the resulting composition by adding the reaction mixture to methanol.

A second method of preparing polymer II, or a method for preparing polymer III, or polyvinyl alcohol containing acetoacetate end groups, consists of dissolving the starting polymer, e.g., polyvinyl alcohol, poly(vinyl acetal) of 2,4-disulfobenzaldehyde or hydroxyethylcellulose in the case of polymer III, in a solvent, e.g., an aqueous solvent such as water or a mixture of water with ethylene glycol. A solution of diketene, e.g., an aqueous solution, is added to the resulting composition. A catalyst which is an organic base, such as an amine, e.g., triethylamine, or an inorganic base, e.g., an alkali metal hyroxide, such as sodium hydroxide or potassium hydroxide, is also added, typically in an aqueous solution. The reaction usually proceeds spontaneously under ambient conditions of temperature and pressure, e.g., at about C. to C. at atmospheric pressure, but elevated temperature and pressure can be employed, if desired. The desired product can be separated, such as by precipitation in an organic solvent, e.g., isopropanol.

Typically, stoichiometric concentrations of reactants are employed.

Typically, the coating compositions from which the described drying element is prepared is coated on a support, such as a support known to be useful in the photographic art which contains a so-called subbing layer, e.g., of gelatin or other polymer as described. However, one embodiment of the invention is an unsupported web of the socalled modifed poly(ethylene oxide) cross-linked with a cross-linking agent, typically an aldehyde, such as formaldehyde, to a polymer the same as the so-called modified poly(ethylene oxide) and/or different from the modified poly(ethylene oxide), e.g., the described polymers II and/or 111 and/or 1V.

Any support, if one is employed, can be used for a drying element according to the invention, provided such a support is coated with gelatin or some such material with which the polymeric components containing acetoacetate end groups of the coating can cross-link. Such a support can be in any suitable shape or form. These include those commonly employed in the photographic art, such as films, including cellulose acetate films, polyester films, such as polyethylene terephthalate films, polyvinyl acetal films, polystyrene films, polycarbonate films, and related materials, paper, e.g., paper supports coated with resinous materials, e.g., coated with polyethylene, polypropylene and/or ethylene-butene copolymers, glass fabrics, metal and the like. Supports in the form of webs and tapes can be used, for example. Supports which act as a reservoir for the diffusible liquid removed are especially suitable. For this reason, absorbent fibrous materials formed from, for example, textiles or glass fibers, paper and/ or similar water absorbent supports can be especially useful.

A wide variety of coating compositions and means for applying them can be employed for preparing the coatings of the invention. In general, any composition, coating means or coating process which provides an adherent coating, having the desired thickness, the desired concentrations of components, and the desired liquid removal properties can be employed.

Various addenda can be present in and/or on the coating and/or support, if one is employed, according to the invention, especially those known to be beneficial in photographic elements, compositions and processes.

A coating composition of the invention, from which a drying element can be prepared, comprises (a) a hydrophilic ethylene oxide polymer containing acetoacetata groups, e.g., polymer I, (b) a cross-linking agent as described, especially an aldehyde, e.g., formaldehyde and (c) a solvent. An especially suitable coating composition comprises a mixture of (a) About 60% to about 90%, by weight, of the total composition solvent, comprising about 10% to about 30% by volume, water and about to about 90%, by volume, Water miscible organic solvent, e.g., water miscible alcohol such as methanol,

(b) About 10% to about 30%, by weight, of the total composition solids soluble in the said solvent comprising about 15% to about 50%, by weight, a synthetic organic polymer, such as polymer Il and/or III, and/or IV, and about 50% to about by Weight, modified organic poly(ethylene oxide), e.g., polymer I, and

(c) About 1% to about 5%, by volume, of cross-linking agent such as an aldehyde, e.g., formaldehyde.

An advantage of coating compositions, as described, is their viscosity before coating. Typically, coating compositions, before application to a support, if one is employed, have a viscosity of about 50 centipoises to about 15,000 centipoises and preferably, a viscosity of about 75 centipoise to about 200 centipoises. The described polymers in the presence of a suitable cross-linking agent, especially an aldehyde, e.g., formaldehyde, rapidly harden under ambient conditions to form a solid. Thus, in coating, the described polymers are typically mixed with the described cross-linking agent shortly before application to a support. The resulting coating on the support rapidly hardens to a firm, adhesive solid. If desired, the support can contain cross-linking agents, such as formaldehyde, e.g., a paper support can contain formaldehyde which aids in adhesion of the coating to the support. Also, if desired, the coating operation can be carried out at elevated temperatures, e.g., at above about 30 C., typically about 30 C. to about C.

Another embodiment of the invention is in a process for removing a diffusible liquid from a permeable solid containing said liquid by contacting said permeable solid with a solid material which removes said liquid from said permeable solid, the improvement which comprises contacting said permeable solid with a drying element comprising an organic, polymeric desiccant cross-linked to an organic polymer. The permeable solid which is contacted by the described drying element can be a moist photographic element.

The drying element of the invention can remove at least about 60%, by weight, of ditfusible liquid, such as Water, in about 1 to about 60 seconds, usually at least 35%, by weight, of water in less than 30 seconds, at

about 20 C. from a solid permeable material, such as a photographic element.

In general, any ditfusible liquid can be removed from a permeable solid according to the invention which is more strongly attracted to a drying element of the invention than said permeable solid when the drying element and permeable solid are intimately contacted. Suitable dilfusible liquids include, for example, water, methanol, liquid lower alkyl amines, such as ethyl amine, and lower alkanol amines, such as ethanol amine and propanol amine.

The invention can be employed in processing of various moist photographic elements. Such photographic elements can be processed before drying in any suitable process employed for this purpose. For example, so-called Web processing can be employed, described, for instance, in U.S. Pat. 3,179,517 of Tregillus et 211., issued Apr. 20, 1965. In the case of photographic elements suitable for color photography containing color forming couplers, one process which is suitable for production of a reversal image consists of the following processing steps and formulas:

1 No reversal exposure may be necessary. The reversal of the image may be accomplished chemically by the inclusion of a reversal agent in the color developer (e.g. butyl amine borane, as cited in the composition of the color developer below).

Chemicals and solutions used in various steps of this process are as follows:

Prehardener:

Water-800.0 ml. p-Toluenesulfinic acid (sodium salt).5 g. Sulfuric acid 18 N5.41 ml. Dimethoxytetrahydrofuran-4.30 ml. Sodium sulfate154.0 g. Sodium bromide2.0 g. Sodium acetate-20.0 g. Formalin (37% by volume, aqueous formaldehyde solution)27.9 ml. N-methyl benzothiazolium-p-toluene sulfonate--.03 g. Waterto 1.0 liter Neutralizer Water-800.0 ml. Hydroxylamine sulfate--22.0 g. Sodium bromide17.0 g. Glacial acetic acid-10.0 ml. Sodium hydroxide6.0 g. Sodium sulfate-5 0.0 g. Water to 1.0 liter First Developer:

Water800.0 ml. Sodium tetraphosphate--2.0 g. Sodium bisulfate--8.0 g. l-phenyl-3-pyrazolidone.35 g. Sodium sulfite37.0 g. Hydroquinone-5 .5 g. Sodium carbonate (anhydrous)28.2 g. Sodium thiocyanate2.6 g. Potassium iodide (0.1% by weight aqueous solution )--6.0 ml. Sodium bromidel .30 g. Water-to 1.0 liter 8 First and second stop bath:

Water800.0 ml. Glacial acetic acid-3 0.0 ml. Sodium hydroxide1.75 g. Waterto 1.0 liter Color Developer:

Water-800.0 ml. Sodium tetraphosphate-S .0 g. Benzyl alcohol4.5 g. Sodium sulfite7.5 g. Trisodium phosphate l2H O-3 6.0 g. Sodium bromide.30 g. Potassium iodide (0.1% by weight, aqueous solution)24.0 ml. Sodium hydroxide-3.25 g. Citrazinic acid-1.50 g. 4-amino-3-methyl-N-ethyl-N-betamethanesulfonamido)ethylaniline sesquisulfate hydrate11.0 g. Tertiary butylamine borane.07 g. Ethylenediarninc3.0 g. Water-to 1.0 liter Ferricyanide bleach:

Water-800.0 ml. Sodium bromide35.0 g. Sodium ferricyanide (decahydrate)-240.0 g. Potassium persulfate-67.0 g. Borax (N32B407 g. Sodium hydroxide. 10 g. Waterto 1.0 liter Fixing bath:

Water-800.0 ml. Sodium thiosulfate (pentahydrate)--200.0 g. Sodium sulfite9.0 g. Water-to 1.0 liter Stabilizing bath:

Water800.0 ml. Formalin-12.0 ml. Water-to 1.0 liter A drying element and/or process of the ina/ention is useful for rapidly removing diifusible liquid, especially water, from a wide variety of photographic elements containing such liquid. For example, it can be used for removing water from any suitable photographic element in a moist condition.

Photographic elements employed in the practice of the invention can contain a layer comprising any of the known water permeable binding materials suitable for photographic purposes. These include, for example, gelatin, colloidal albumin, cellulose derivatives, polymerized vinyl compounds, acrylamide polymers, as well as mixtures of such binding agents. These binding agents can contain water insoluble polymers, such as polymerized ethylenically unsaturated compounds, e.g., water insoluble polymers of acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates and the like.

The photographic elements which can be dried according to the invention include those which contain conventional addenda such as plasticizers, coating aids,

antifoggants, such as the azaindenes, and hardeners, such as aldehyde hardeners, e.g., formaldehyde, mucochloric acid, glutaraldehyde bis(sodium bisulfite), maleic dialdehyde, aziridines, dioxane derivatives and oxypolysac charides. Sensitizing dyes useful in sensitizing such emulsions are described, for example, in U.S. Pats. 2,526,632 of Brooker and White, issued Oct. 24, 1950, and 2,503,776 of Sprague, issued April 11, 1950. Spectral sensitizers which can be used are the cyanines, merocyanines, complex (trinuclear) cyanines, complex (trinuclear) merocyanines, styryls, and hemicyanines. Developing agents can also be incorporated into the emulsion if desired or can be contained in a separate contiguous layer. Various silver salts can be used as the sensitive salt, such as silver bromide, silver iodide, silver chloride or mixed silver halides, such as silver chloro- 9 bromide or silver bromoiodide. The silver halides used can be those which form latent images predominantly on the surface of the silver halide grains or those which form latent images inside the silver halide crystals such as described in US. Pat. 2,592,250 of Davey and Knott, issued Apr. 8, 1952.

Photographic elements dried in the practice of the invention can also contain speed increasing compounds such as quaternary ammonium compounds, polyethylene glycols or thioethers. Frequently, useful elfects can be obtained by adding the aforementioned speed increasing compounds to photographic developer solution employed for processing instead of, or in addition to, the photographic emulsions.

The invention can be used to dry a layer of a photographic element intended for color photography, for example, emulsions containing color-forming couplers or emulsions to be developed by solutions containing couplers or other color-generating materials, emulsions of the mixed-packet type such as described in US. Pat. 2,698,794 of Godowsky, issued Ian. 4, 1955; in silver dye-bleach systems and emulsions of the mixed-grain type such as described in US. Pat. 2,592,243 of Carroll and Hanson, issued Apr. 8, 1952.

Photographic emulsions or elements dried in the practice of the invention can be sensitized using any of the well known techniques in emulsion making, for example, by digesting with naturally active gelatin or various sulfur, selenium, tellurium and/or noble metal sensitizers. Combinations of sensitizers can be employed, such as described in U.S. Pat. 3,297,446 of Dunn, issued Jan. 10, 1967, and US. Pat. 3,408,196 of McVeigh, issued Oct. 29, 1968.

The drying elements and/ or processes of the invention can be employed in the production of layers of liquid permeable solid materials. For instance, liquid permeable, drying elements and processes of the invention can be employed in the production of layers of unexposed photographic elements which require removal of water and/or other suitable liquid at some stage. A typical process according to the invention for the production of a layer of a photographic element accordingly comprises applying a hydrophilic colloid coating to a substrate, the resulting coating containing water and/ or other suitable liquid, and subsequently contacting the hydrophilic colloid coating with a liquid permeable, drying element, as described, comprising an organic, polymeric desiccant, to remove a substantial portion of the water and/ or other suitable liquid from the hydrophilic colloid coating.

A wide range of coating methods and conditions can be employed for preparing the coatings from which liquids, e.g., water, can be removed according to the invention. In general, coating methods, compositions, and conditions commonly employed in the photographic art can be employed.

A typical method for production of a raw photographic emulsion layer comprises applying a coating of a photographic emulsion to a substrate, setting the resulting coating, such as by chilling or fuming with ammonia in the case of gelatino emulsion coatings, and contacting the resulting coating with a liquid permeable, drying element, as described, comprising an organic, polymeric desiccant, such as contacted with a supported or unsupported coating, as described, containing a so-called modified poly- (ethylene oxide), e.g., a so-called modified poly(ethylene oxide) containing acetoacetate groups cross-linked with formaldehyde to a polymer II, III and/or IV and to a gelatin coated support, to remove a substantial portion of the water from the raw photographic emulsion coating.

The raw photographic emulsion coating can be contacted using essentially the same conditions and time of contact as employed for contacting exposed and processed, wet photographic elements to effect removal of water.

The time of contact of the described drying element with the permeable solid to be dried required for drying,

especially a photographic element, is typically about 1 second to about 60 seconds, although, if desired, a contact time of 1 minute to several minutes can be employed. When the desired degree of removal of diffusible liquid from the permeable solid is reached, then the drying element is usually removed from contact with the material dried.

Any suitable method or means can be employed for contacting the described drying element with the material to be dried. For example, in the case of a moist strip of photographic film, the described drying element, e.g., a flexible web coated with gelatin and the described so-called modified poly(ethylene oxide) in the presence of a cross-linking agent, can be rolled in contact with the photographic film on, for instance, a spindle, for about 5 to about 60 seconds.

The described drying element can be in any suitable form, such as, in the form of a drum or solid, flat surface or can be a flexible web.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 l on and is precipitated in isopropanol. Analysis indicates a polymer containing a mole ratio of alcohol moiety to aceto acetate moiety, i.e., the ratio of x to y, is 129:1.

The average molecular weight is about 1000 to about 10,000.

EXAMPLE 2 This illustrates preparation of a polymer employed in the practice of the invention as in Example 1.

22 grams of polyvinyl alcohol is dissolved in 196 grams of water and cooled to 15 C. One gram of triethylamine is added. 4.2 grams of diketene is then added with stirring. Stirring is continued for one hour at atmospheric pressure. Pressure is then reduced and the reactant mixture heated on a steam bath for 15 minutes. The product is then cooled and a small sample is precipitated in isopropanol. Analysis of the desired product indicates a mole ratio of x to y of 72:1 based on the alcohol moiety to aceto acetate moiety represented by the formula in Example 1.

EXAMPLE 3 This illustrates preparation of a polymer as in Example l.

44 grams of polyvinyl alcohol is dissolved in 478 ml. of water and cooled to about 15 C. The pH of the solutron is adjusted to 9.0 by the addition of sodium hydroxide. 8.4 grams of diketene is added with vigorous stirring. The pH of the resulting solution is adjusted to between 7.0 and 8.0 with the gradual addition of aqueous sodium hydroxide solution. A total of about 70 ml. of aqueous sodium hydroxide solution containing 2.5% by Weight sodium hydroxide is added. The pH of the final reactant solution is about 5.5. Pressure is reduced from atmospheric pressure and the mixture heated on a steam 11 bath for 15 minutes. It is then cooled and the desired product is precipitated from isopropanol. The desired product has a mole ratio of x to y of 37:1 based on the alcohol moiety and aceto acetate moiety as set out in the formula set out in Example 1.

EXAMPLE 4 This illustrates preparation of a polymer as in Example 1.

792 grams of polyvinyl alcohol is dissolved in 7200 ml. of water and the resulting solution cooled to about 15 C. 150 grams of diketene is then added with vigorous stirring. The pH of the resulting mixture is adjusted to 7.0 to 8.5 with gradual addition of aqueous sodium hydroxide solution containing 10% by weight sodium hydroxide. After addition of 315 ml. of sodium hydroxide solution the pH of the reactant mixture gradually drops to 5.5. The desired product, as shown by the formula set out in Example 1 is produced.

EXAMPLE 5 Two liters is prepared of an aqueous solution containing about 8% by weight of the disodium salt of a copolymer having repeating units of the formula:

| SOzNa wherein the mole ratio of x to y is about 20.5 to 1. The solution is cooled to about 10-15 C. and 32 g. of diketene is added with vigorous stirring. The pH of the solution is adjusted to between 7.0 and 8.5 with the addition of 10% by weight aqueous sodium hydroxide solution. After the addition of 32 ml. of sodium hydroxide solution, the pH drops slowly to 4.0, yielding the desired polymeric product having repeating units of the formula:

1 SOsNa wherein the mole ratio of x to y to z is about 215 to 10.6 to 1 respectively. The average molecular weight of the polymer is about 1000 to about 10,000.

EXAMPLE 6 EXAMPLE 7 This illustrates preparation of a so-called modified poly(ethylene oxide) within described Formula I.

A preparation is carried out as described in Exampie 1 with the exception that poly (ethylene oxide) having an average molecular weight of about 5000 to about 7000 is employed in place of polyvinyl alcohol. The resulting polymer contains acetoacetate end groups and is believed to be of the formula:

wherein n is about to about 200.

EXAMPLE 8 This illustrates preparation of a drying element according to the invention.

A portion of a 1 liter aqueous solution containing (a) grams of a polymer of Formula IV as prepared in Example 1; (b) grams of a modified poly(ethylene oxide) as prepared in Example 7; and (c) 4.5 grams of formaldehyde is hand-coated on polyethylene terephthalate film support, containing a subcoat of gelatin, to give an approximate dry coverage of 15 grams of solids/ft. (thickness 5.3 mils). The coating contains approximately 6 grams/ft. of a polymer of Formula IV and 9 grams/ft. of the described modified poly(ethylene oxide). The resulting coating is permitted to solidify under atmospheric conditions.

EXAMPLE 9 This illustrates drying a moist photographic element according to the invention.

Several samples of the drying element prepared in the manner described in Example 8 are intimately contacted (by hand roller) for varying periods of time with moist samples of a photographic color reversal film which had been processed after sensitometric exposure.

The film is a polyethylene terephthalate support containing respectively on the support (a) a red sensitive gelatino silver bromoiodide emulsion containing a cyan dye forming coupler, (b) a clear gelatin layer, (c) a green sensitive gelatino silver bromoiodide emulsion containing a magenta dye forming coupler, (d) a Carey Lea silver layer and (e) a blue sensitive gelatino silver bromoiodide emulsion containing a yellow dye forming coupler. The film is 35 mm. wide and about 25.4 centimeters long. After sensitometric exposure, it is processed in a reversal process as herein described. Drying of the resulting moist film is carried out by pressing the emulsion side of the film in direct contact for varying lengths of time with a drying element as described in Example 7, as set out in Table I. The total percentage of water remaining in the film after direct contact with the drying element is calculated by (a) measuring the thickness of the film (including the support) with a micrometer immediately after processing but before drying and (b) again after drying. The thickness measurement after processing but before drying is taken as a moisture content of TABLE I Relative percent of water Contact time (see): left in emulsion EXAMPLE 10 This illustrates preparation of a drying element according to the invention.

A portion of a l-liter aqueous solution containing (a) 37.5 grams of a polymer as described in Example 1, (b) 102.5 grams of a polymer as described in Example 7 and (c) 4.5 grams of formaldehyde is hand-coated on a polyethylene terephthalate film support containing a gelatino subcoat to give an approximate dry coverage of 17 grams solids/ft. (thickness 6 mils), The coating contains approximately 4.25 grams of a polymer as described in Example 1 and 12.75 grams of a polymer as described in Several samples of the drying element prepared as in Example 10 are tested by the procedure described in Example 9. The results are tabulated in Table II.

TABLE II Relative percent of water Contact time (sec.): left in emulsion EXAMPLE 12 A portion of a 1-liter aqueous solution containing (a) 22.5 grams of a polymer as described in Example 1, (b) 127.5 grams of a polymer as described in Example 7 and (c) 4.5 grams of formaldehyde is hand-coated on polyethylene terephthalate fihn support containing a gelatino subcoat to give an approximate dry coverage of 17 grams of solids/ft. (thickness 6 mils). The coating contains approximately 2.55 grams/ft. of a polymer as described in Example 1 and 14.45 grams/ft. of a polymer as described in Example 7 (modified ethylene oxide polymer). The coating is permitted to solidify under atmospheric conditions.

EXAMPLE 13 Several samples of the drying element prepared as described in Example 12 are tested by the procedure described in Example 8. The results are tabulated in Table III.

TABLE III Relative percent of water Contact time (sec.): left in emulsion O 100 30 31 60 13 120 ll EXAMPLE 14 EXAMPLE 15 Several samples of the drying element prepared as described in Example 14 are tested by the procedure described in Example 8. The results are tabulated in Table IV.

TABLE IV Relative percent of water Contact time (sec.): left in emulsion 0 100 EXAMPLE 16 A portion of a 1-liter aqueous solution containing (a) 45 grams of a polymer prepared as described in Example 1; (b) 105 grams of a polymer prepared as in Example 7 and (c) 4.5 grams of formaldehyde is hand-coated on a polyethylene terephthalate film support containing a gelatino subcoat to provide an approximate dry coverage of 14 8.5 grams solids/ft. (thickness 3 mils). The coating contains approximately 2.55 grams/ft. of a polymer prepared as described in Example 1 and 5.9-5 grams/ft. of a polymer prepared as described in Example 7. The resulting coating is permitted to solidify under atmospheric conditions.

EXAMPLE 17 Several samples of the drying element as prepared in Example 16 are tested by the procedure described in Example 8. The results are tabulated in Table V.

TABLE V Relative percent of water Contact time (sec.): left in emulsion EXAMPLE 18 A portion of a 1-liter aqueous solution containing (a) 45 grams of a polymer as prepared in Example 1; (b) grams of a polymer as prepared in Example 7 and (c) 4.5 grams of formaldehyde is machine-coated on support to give an approximate dry coverage of 8.5 grams solids/ ft. (thickness 3 mils). The coating contains approximately 2.55 grams/ft. of a polymer as prepared in Example 7 and 5.95 grams/ft. of a polymer as prepared in Example 7.

Several samples of this drying element are tested by the procedure described in Example 1. The results are tabulated in Table VI.

TABLE VI Relative percent of water Contact time (sec.): left in emulsion A residual polymer test is carried out on the above dried photographic elements and an amount of less than 6 mg./ft. is detected. Also, by visual and observation tests none are waxy to the touch or feel greasy or show fingerprints. The conclusion is that no objectionable amount of desiccant is transferred to the photographic element being dried.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be elIected within the spirit and scope of the invention.

We claim:

1. A solid, liquid-permeable, drying element comprising an organic polymeric desiccant cross-linked to an organic polymer.

2. A solid, liquid-permeable, drying element as in claim 1 wherein said organic polymeric desiccant is a hydrophilic ethylene oxide polymer cross-linked with an aldehyde to said organic polymer.

3. A solid, liquid-permeable, drying element as in claim 1 comprising a hydrophilic ethylene oxide polymer crosslinked with formaldehyde to gelatin.

4. A solid, liquid-permeable, drying element as in claim 1 comprising (a) a support containing thereon (b) gelatin and (c) an organic polymeric desiccant which is (i) a polymer which is acetoacetylated poly(ethylene oxide) which polymer is cross-linked to said gelatin with (ii) formaldehyde.

5. A solid, liquid-permeable, drying element as in claim 1 comprising (a) a support containing thereon (b) gelatin and (c) an organic polymeric desiccant which is (i) a polymer which is the acetal of disodium 2,4-disulfobenzaldehyde and copoly(vinyl alcohol-vinyl acetoacetate) which polymer is cross-linked to said gelatin with (ii) formaldehyde.

6. A solid, liquid-permeable, drying element as in claim 1 comprising (a) a support containing thereon (b) gelatin and (c) an organic polymeric desiccant which is (i) a polymer which is acetoacetylated hydroxy ethyl cellulose which polymer is cross-linked to said gelatin with (ii) formaldehyde.

7. A coating composition comprising (a) a hydrophilic polymer containing acetoacetate groups, (b) an aldehyde and (c) a solvent.

8. A coating composition as in claim 7 comprising an aqueous solution having a viscosity of 75 to 200 centipoises at 20 C.

9. A coating composition as in claim 7 wherein said hydrophilic polymer is acetoacetylated poly(ethylene oxide).

10. A coating composition as in claim 7 wherein said hydrophilic polymer is the acetal of disodium 2,4-disulfobenzaldehyde and copoly (vinyl alcohol-vinyl acetoacetate).

11. A coating composition as in claim 7 wherein said hydrophilic polymer is acetoacetylated hydroxy ethyl cellulose.

12. In a process for removing a ditfusible liquid from a permeable solid containing said liquid by contacting said permeable solid with a solid material which rernoves said liquid from said permeable solid, the improvement comprising contacting said permeable solid with a drying element comprising an organic polymeric desiccant cross-linked to an organic polymer.

13. A process as in claim 12 wherein said permeable solid is a photographic element.

14. A process as in claim 12 wherein said diifusibie liquid is water.

15. A process as in claim 12 wherein said drying element comprises said organic polymeric desiccant which is acetoacetylated poly(ethylene oxide) cross-linked with an aldehyde to said organic polymer.

16. A process as in claim 12 wherein at least about 60% by weight of said liquid is removed from said permeable solid containing said liquid in about 1 to about 60 seconds at about 20 C.

17. A process for removing moisture from a moist photographic element which comprises directly contacting said photographic element with a solid liquid permeable drying element comprising an organic polymeric desiccant cross-linked to an organic polymer.

18. A process as in claim 17 wherein moisture is removed from a moist photographic element by contacting said element for up to about 60 seconds under ambient conditions of temperature, pressure and humidity with a drying element comprising (a) a support having thereon, (b) gelatin and (c) an organic polymeric desiccant which comprises acetoacetylated poly(ethylene oxide) crosslinked to said gelatin.

19. A process as in claim 18 wherein said organic polymeric desiccant comprises (i) acetoacetylated poly(ethylene oxide) and (ii) the acetal of disodium 2,4-disulfobenzaldehyde and copoly(vinyl alcohol-vinyl acetoacetate) cross-linked with formaldehyde to said gelatin.

20. A process as in claim 18 wherein said organic polymeric desiccant comprises (i) acetoacetylated poly(ethy1- ene oxide) and (ii) the acetoacetylated hydroxy ethyl cellulose cross-linked with formaldehyde to said gelatin.

21. A solid organic polymeric desiccant composition comprising (i) an acetoacetylated poly(ethylene oxide) and (ii) the acetal of disodium 2,4-disulfobenzaldehyde and copoly(vinyl alcohol-vinyl acetoacetate) cross-linked with an aldehyde.

22. A solid organic polymeric desiccant composition comprising (i) an acetoacetylated poly-(ethylene oxide) and (ii) acetoacetylated hydroxy ethyl cellulose crosslinked with an aldehyde.

References Cited UNITED STATES PATENTS 2,156,757 3/1939 Bodine 349X 3,384,971 5/1968 Thomas, Jr., et a1. 34-9 3,448,528 6/ 1969 Jackson et a]. 1 349 JOHN J. CAMBY, Primary Examiner 

